The present invention relates to a method and device used in intravascular therapeutic and diagnostic procedures and in particular to a method and device for use in facilitating a guide wire exchange.
Intravascular therapeutic and diagnostic techniques have developed, such as angioplasty, for treating certain vascular diseases. These techniques are an alternative to surgery and have proved quite successful. These techniques are particularly useful for treating certain types of coronary heart disease.
Therapeutic or diagnostic devices used to treat vascular diseases are typically formed of an elongated tubular member designed to extend from outside the patient through the vasculature of a patient to a treatment site. Some therapeutic or diagnostic intravascular devices (e.g., Percutaneous Transluminal Coronary Angioplasty ("PTCA") balloon catheters) are designed for use and insertion in combination with a steerable guide wire ("over-the-wire" type intravascular devices). Over-the-wire type devices include a guide wire lumen through which the guide wire is inserted for use in advancing the device to a treatment site.
A guide wire is designed to extend to a treatment site while a portion of the guide wire remains outside the patient for control. A distal tip portion of the guide wire typically is formed of a flexible construction. The flexible tip construction allows the operator to shape the distal tip and therefore navigate tortuous anatomy. An operator forms a bend on the distal tip to facilitate insertion and advancement of the guide wire so that the guide wire may be steered to the treatment site through the patient's vasculature.
The formed distal tip of a guide wire is sometimes discovered to be inappropriately shaped so that it is difficult to steer the guide wire to the treatment site, thereby making it extremely difficult for the operator to advance the intravascular device over the guide wire to the treatment site. Or, the distal tip of a pre-inserted guide wire may have been appropriate to track the guide wire to a first lesion but the distal tip is inappropriate to track to a second lesion requiring treatment. Accordingly, it is then necessary to withdraw the original guide wire to reshape its distal tip or substitute an alternately shaped guide wire therefor.
Alternatively, the guide wire inserted may be discovered to be too stiff or too flexible and it may be desirable to substitute a different guide wire with different properties. This procedure of withdrawing a guide wire previously inserted into a patient and reinserting a reshaped guide wire or a substitute guide wire is referred to as a "guide wire exchange."
In some "over-the-wire" intravascular device constructions, the guide wire lumen extends the entire length of the intravascular device so that a proximal opening to the guide wire lumen is positioned outside of the patient. Accordingly, if a guide wire exchange is necessary in a situation where the intravascular device and guide wire are already in place adjacent the treatment site in the patient's vasculature, the guide wire is withdrawn from the guide wire lumen of the device and a substitute guide wire is inserted through the exposed proximal opening of the guide wire lumen and advanced to a treatment site. Since the guide wire lumen extends along the entire length of the device, the substitute or reshaped guide wire is directed by the guide wire lumen through the vasculature of the patient to a treatment site.
Alternate "over-the-wire" device constructions have a guide wire lumen which does not extend along the entire length of the device. These devices are sometimes referred to as "single operator exchange" devices. The guide wire lumen of a "single operator exchange" device extends only along a distal portion of the device such that the proximal opening to the guide wire lumen is inside the patient when the device is inserted into the patient to a treatment site.
In such a device, like the Express.RTM. balloon catheter made by SciMed Life Systems, Inc. of Maple Grove, Minn., a guide wire exchange is virtually impossible without moving the device proximally out of the patient to expose the proximal opening of its guide wire lumen. If the device is left in place in the patient and only the initially inserted guide wire is removed, it is extremely difficult, if not impossible, to locate and re-insert a reshaped or substitute guide wire into the small proximal opening of the "single operator exchange" device (which is not exposed outside the patient). Thus, when the initial guide wire for the device is removed, an operator is unable to maintain the device in position for inserting a reshaped or substitute guide wire into the patient for further treatment. Accordingly, the physician must retrace the entire tortuous path through the patient to the treatment site to reinsert a guide wire for treatment (which can be time consuming).
Revised catheter constructions or other devices have been proposed to allow a guide wire exchange when using a "single operator exchange" device. Such arrangements are shown, for example, in Kramer, U.S. Pat. No. 5,135,535 and Shockey et al., U.S. Pat. Nos. 4,932,413 and 4,947,864. In these examples, modification of the "single operator exchange" device is required or simultaneous control of multiple wires within the patient at times during the guide wire exchange procedure is required. Another approach to allow the exchange of a guide wire in a single operator exchange device is shown in copending U.S. patent application Ser. No. 07/725,064, filed Jul. 5, 1991, entitled "Guide Wire Sheath Method and Apparatus for Single Operator Exchange Catheter or Similar Device" (Ressemann), and which is owned by the assignee of the instant application (SciMed Life Systems, Inc. of Maple Grove, Minn. ) and incorporated by reference herein in its entirety. In this arrangement, a guide wire sheath extends over the guide wire and through the guide wire lumen of the device. Thus, when a guide wire exchange is performed, the sheath retains the path for the guide wire from outside the patient into and through the guide wire lumen of the single operator exchange device.